Homogenizer

Abstract

A two-stage homogenizer comprising a first homogenizer stage and a second homogenizer stage. The first homogenizer stage includes a pair of microlens arrays and associated focusing optics. The second homogenizer stage includes a second pair of microlens arrays and associated focusing optics. The second homogenizer stage is positioned to receive radiation which is output from the first homogenizer stage.

What is claimed is: 
     
       1. A two-stage homogenizer comprising:
 a first homogenizer stage comprising a first pair of microlens arrays and associated focusing optics; 
 a second homogenizer stage comprising a second pair of microlens arrays and associated focusing optics, the second homogenizer stage being positioned to receive radiation that is output from the first homogenizer stage, wherein the first and second pairs of microlens arrays are two-dimensional microlens arrays; 
 a detector configured to detect a diameter of a radiation beam incident upon the first homogenizer stage; and 
 a processor configured to determine a peak intensity of the radiation beam in a second microlens array of the second pair of microlens arrays based upon the detected diameter of the radiation beam. 
 
     
     
       2. The two-stage homogenizer of  claim 1 , wherein a second microlens array of the first pair of microlens arrays does not lie in a focal plane of a first microlens array of the first pair of microlens arrays. 
     
     
       3. The two-stage homogenizer of  claim 1 , wherein each of the focusing optics of the first and second homogenizer stages comprises one or more condensing lenses. 
     
     
       4. The two-stage homogenizer of  claim 1 , further comprising adjusting optics configured to provide adjustment of the diameter of the radiation beam in response to a detected diameter of the radiation beam. 
     
     
       5. An illumination system comprising:
 a first homogenizer stage comprising a first pair of microlens arrays and associated focusing optics; 
 a second homogenizer stage comprising a second pair of microlens arrays and associated focusing optics, the second homogenizer stage being positioned to receive radiation that is output from the first homogenizer stage, wherein the first and second pairs of microlens arrays are two-dimensional microlens arrays; 
 an array of individually controllable elements configured to receive radiation output from the second homogenizer stage; 
 a detector configured to detect a diameter of a radiation beam incident upon the first homogenizer stage; and 
 a processor configured to determine a peak intensity of the radiation beam in a second microlens array of the second pair of microlens array based upon the detected diameter of the radiation beam. 
 
     
     
       6. A lithographic apparatus comprising:
 a first homogenizer stage comprising a first pair of microlens arrays and associated focusing optics; 
 a second homogenizer stage comprising a second pair of microlens arrays and associated focusing optics, the second homogenizer stage being positioned to receive radiation that is output from the first homogenizer stage, wherein the first and second pairs of microlens arrays are two-dimensional microlens arrays; 
 an array of individually controllable elements configured to receive radiation output from the second homogenizer stage; 
 a detector configured to detect a diameter of a radiation beam incident upon the first homogenizer stage; and 
 a processor configured to determine a peak intensity of the radiation beam in a second microlens array of the second pair of microlens arrays based upon the detected diameter of the radiation beam. 
 
     
     
       7. A method of homogenizing a radiation beam comprising:
 passing the radiation beam through a first pair of microlens arrays; 
 passing the radiation beam through focusing optics; 
 passing the radiation beam through a second pair of microlens arrays, wherein the first and second pairs of microlens arrays are two-dimensional microlens arrays; 
 passing the radiation beam through additional focusing optics; 
 detecting a diameter of the radiation beam; and 
 determining a peak intensity of the radiation beam in a second microlens array of the second pair of microlens arrays based upon the detected radiation beam diameter. 
 
     
     
       8. The method of  claim 7 , wherein a second microlens array of the first pair of microlens arrays does not lie in a focal plane of a first microlens array of the first pair of microlens arrays. 
     
     
       9. The method of  claim 7 , wherein each of the focusing optics of the first and second homogenizer stages comprises one or more condensing lenses. 
     
     
       10. The method of  claim 7 , wherein the method further comprises adjusting the diameter of the radiation beam in response to a determined peak intensity. 
     
     
       11. The method of  claim 7 , wherein the method further comprises passing the homogenized radiation from the homogenizer to an array of individually controllable elements.